510 lines
16 KiB
C
510 lines
16 KiB
C
//========================================================================
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// Heightmap example program using OpenGL 3 core profile
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// Copyright (c) 2010 Olivier Delannoy
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//
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// This software is provided 'as-is', without any express or implied
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// warranty. In no event will the authors be held liable for any damages
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// arising from the use of this software.
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//
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// Permission is granted to anyone to use this software for any purpose,
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// including commercial applications, and to alter it and redistribute it
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// freely, subject to the following restrictions:
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//
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// 1. The origin of this software must not be misrepresented; you must not
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// claim that you wrote the original software. If you use this software
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// in a product, an acknowledgment in the product documentation would
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// be appreciated but is not required.
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//
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// 2. Altered source versions must be plainly marked as such, and must not
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// be misrepresented as being the original software.
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//
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// 3. This notice may not be removed or altered from any source
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// distribution.
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//
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//========================================================================
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#include <stdlib.h>
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#include <stdio.h>
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#include <math.h>
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#include <assert.h>
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#include <stddef.h>
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#include <glad/glad.h>
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#include <GLFW/glfw3.h>
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/* Map height updates */
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#define MAX_CIRCLE_SIZE (5.0f)
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#define MAX_DISPLACEMENT (1.0f)
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#define DISPLACEMENT_SIGN_LIMIT (0.3f)
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#define MAX_ITER (200)
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#define NUM_ITER_AT_A_TIME (1)
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/* Map general information */
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#define MAP_SIZE (10.0f)
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#define MAP_NUM_VERTICES (80)
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#define MAP_NUM_TOTAL_VERTICES (MAP_NUM_VERTICES*MAP_NUM_VERTICES)
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#define MAP_NUM_LINES (3* (MAP_NUM_VERTICES - 1) * (MAP_NUM_VERTICES - 1) + \
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2 * (MAP_NUM_VERTICES - 1))
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/**********************************************************************
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* Default shader programs
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*********************************************************************/
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static const char* vertex_shader_text =
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"#version 150\n"
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"uniform mat4 project;\n"
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"uniform mat4 modelview;\n"
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"in float x;\n"
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"in float y;\n"
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"in float z;\n"
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"\n"
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"void main()\n"
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"{\n"
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" gl_Position = project * modelview * vec4(x, y, z, 1.0);\n"
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"}\n";
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static const char* fragment_shader_text =
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"#version 150\n"
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"out vec4 color;\n"
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"void main()\n"
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"{\n"
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" color = vec4(0.2, 1.0, 0.2, 1.0); \n"
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"}\n";
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/**********************************************************************
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* Values for shader uniforms
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*********************************************************************/
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/* Frustum configuration */
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static GLfloat view_angle = 45.0f;
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static GLfloat aspect_ratio = 4.0f/3.0f;
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static GLfloat z_near = 1.0f;
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static GLfloat z_far = 100.f;
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/* Projection matrix */
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static GLfloat projection_matrix[16] = {
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1.0f, 0.0f, 0.0f, 0.0f,
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0.0f, 1.0f, 0.0f, 0.0f,
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0.0f, 0.0f, 1.0f, 0.0f,
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0.0f, 0.0f, 0.0f, 1.0f
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};
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/* Model view matrix */
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static GLfloat modelview_matrix[16] = {
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1.0f, 0.0f, 0.0f, 0.0f,
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0.0f, 1.0f, 0.0f, 0.0f,
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0.0f, 0.0f, 1.0f, 0.0f,
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0.0f, 0.0f, 0.0f, 1.0f
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};
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/**********************************************************************
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* Heightmap vertex and index data
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*********************************************************************/
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static GLfloat map_vertices[3][MAP_NUM_TOTAL_VERTICES];
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static GLuint map_line_indices[2*MAP_NUM_LINES];
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/* Store uniform location for the shaders
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* Those values are setup as part of the process of creating
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* the shader program. They should not be used before creating
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* the program.
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*/
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static GLuint mesh;
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static GLuint mesh_vbo[4];
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/**********************************************************************
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* OpenGL helper functions
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*********************************************************************/
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/* Creates a shader object of the specified type using the specified text
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*/
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static GLuint make_shader(GLenum type, const char* text)
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{
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GLuint shader;
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GLint shader_ok;
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GLsizei log_length;
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char info_log[8192];
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shader = glCreateShader(type);
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if (shader != 0)
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{
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glShaderSource(shader, 1, (const GLchar**)&text, NULL);
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glCompileShader(shader);
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glGetShaderiv(shader, GL_COMPILE_STATUS, &shader_ok);
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if (shader_ok != GL_TRUE)
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{
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fprintf(stderr, "ERROR: Failed to compile %s shader\n", (type == GL_FRAGMENT_SHADER) ? "fragment" : "vertex" );
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glGetShaderInfoLog(shader, 8192, &log_length,info_log);
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fprintf(stderr, "ERROR: \n%s\n\n", info_log);
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glDeleteShader(shader);
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shader = 0;
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}
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}
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return shader;
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}
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/* Creates a program object using the specified vertex and fragment text
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*/
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static GLuint make_shader_program(const char* vs_text, const char* fs_text)
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{
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GLuint program = 0u;
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GLint program_ok;
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GLuint vertex_shader = 0u;
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GLuint fragment_shader = 0u;
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GLsizei log_length;
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char info_log[8192];
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vertex_shader = make_shader(GL_VERTEX_SHADER, vs_text);
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if (vertex_shader != 0u)
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{
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fragment_shader = make_shader(GL_FRAGMENT_SHADER, fs_text);
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if (fragment_shader != 0u)
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{
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/* make the program that connect the two shader and link it */
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program = glCreateProgram();
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if (program != 0u)
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{
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/* attach both shader and link */
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glAttachShader(program, vertex_shader);
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glAttachShader(program, fragment_shader);
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glLinkProgram(program);
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glGetProgramiv(program, GL_LINK_STATUS, &program_ok);
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if (program_ok != GL_TRUE)
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{
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fprintf(stderr, "ERROR, failed to link shader program\n");
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glGetProgramInfoLog(program, 8192, &log_length, info_log);
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fprintf(stderr, "ERROR: \n%s\n\n", info_log);
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glDeleteProgram(program);
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glDeleteShader(fragment_shader);
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glDeleteShader(vertex_shader);
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program = 0u;
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}
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}
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}
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else
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{
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fprintf(stderr, "ERROR: Unable to load fragment shader\n");
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glDeleteShader(vertex_shader);
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}
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}
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else
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{
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fprintf(stderr, "ERROR: Unable to load vertex shader\n");
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}
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return program;
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}
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/**********************************************************************
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* Geometry creation functions
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*********************************************************************/
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/* Generate vertices and indices for the heightmap
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*/
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static void init_map(void)
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{
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int i;
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int j;
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int k;
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GLfloat step = MAP_SIZE / (MAP_NUM_VERTICES - 1);
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GLfloat x = 0.0f;
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GLfloat z = 0.0f;
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/* Create a flat grid */
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k = 0;
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for (i = 0 ; i < MAP_NUM_VERTICES ; ++i)
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{
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for (j = 0 ; j < MAP_NUM_VERTICES ; ++j)
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{
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map_vertices[0][k] = x;
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map_vertices[1][k] = 0.0f;
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map_vertices[2][k] = z;
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z += step;
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++k;
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}
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x += step;
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z = 0.0f;
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}
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#if DEBUG_ENABLED
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for (i = 0 ; i < MAP_NUM_TOTAL_VERTICES ; ++i)
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{
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printf ("Vertice %d (%f, %f, %f)\n",
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i, map_vertices[0][i], map_vertices[1][i], map_vertices[2][i]);
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}
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#endif
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/* create indices */
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/* line fan based on i
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* i+1
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* | / i + n + 1
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* | /
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* |/
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* i --- i + n
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*/
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/* close the top of the square */
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k = 0;
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for (i = 0 ; i < MAP_NUM_VERTICES -1 ; ++i)
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{
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map_line_indices[k++] = (i + 1) * MAP_NUM_VERTICES -1;
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map_line_indices[k++] = (i + 2) * MAP_NUM_VERTICES -1;
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}
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/* close the right of the square */
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for (i = 0 ; i < MAP_NUM_VERTICES -1 ; ++i)
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{
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map_line_indices[k++] = (MAP_NUM_VERTICES - 1) * MAP_NUM_VERTICES + i;
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map_line_indices[k++] = (MAP_NUM_VERTICES - 1) * MAP_NUM_VERTICES + i + 1;
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}
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for (i = 0 ; i < (MAP_NUM_VERTICES - 1) ; ++i)
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{
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for (j = 0 ; j < (MAP_NUM_VERTICES - 1) ; ++j)
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{
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int ref = i * (MAP_NUM_VERTICES) + j;
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map_line_indices[k++] = ref;
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map_line_indices[k++] = ref + 1;
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map_line_indices[k++] = ref;
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map_line_indices[k++] = ref + MAP_NUM_VERTICES;
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map_line_indices[k++] = ref;
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map_line_indices[k++] = ref + MAP_NUM_VERTICES + 1;
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}
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}
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#ifdef DEBUG_ENABLED
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for (k = 0 ; k < 2 * MAP_NUM_LINES ; k += 2)
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{
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int beg, end;
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beg = map_line_indices[k];
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end = map_line_indices[k+1];
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printf ("Line %d: %d -> %d (%f, %f, %f) -> (%f, %f, %f)\n",
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k / 2, beg, end,
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map_vertices[0][beg], map_vertices[1][beg], map_vertices[2][beg],
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map_vertices[0][end], map_vertices[1][end], map_vertices[2][end]);
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}
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#endif
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}
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static void generate_heightmap__circle(float* center_x, float* center_y,
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float* size, float* displacement)
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{
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float sign;
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/* random value for element in between [0-1.0] */
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*center_x = (MAP_SIZE * rand()) / (1.0f * RAND_MAX);
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*center_y = (MAP_SIZE * rand()) / (1.0f * RAND_MAX);
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*size = (MAX_CIRCLE_SIZE * rand()) / (1.0f * RAND_MAX);
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sign = (1.0f * rand()) / (1.0f * RAND_MAX);
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sign = (sign < DISPLACEMENT_SIGN_LIMIT) ? -1.0f : 1.0f;
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*displacement = (sign * (MAX_DISPLACEMENT * rand())) / (1.0f * RAND_MAX);
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}
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/* Run the specified number of iterations of the generation process for the
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* heightmap
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*/
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static void update_map(int num_iter)
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{
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assert(num_iter > 0);
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while(num_iter)
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{
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/* center of the circle */
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float center_x;
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float center_z;
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float circle_size;
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float disp;
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size_t ii;
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generate_heightmap__circle(¢er_x, ¢er_z, &circle_size, &disp);
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disp = disp / 2.0f;
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for (ii = 0u ; ii < MAP_NUM_TOTAL_VERTICES ; ++ii)
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{
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GLfloat dx = center_x - map_vertices[0][ii];
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GLfloat dz = center_z - map_vertices[2][ii];
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GLfloat pd = (2.0f * sqrtf((dx * dx) + (dz * dz))) / circle_size;
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if (fabs(pd) <= 1.0f)
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{
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/* tx,tz is within the circle */
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GLfloat new_height = disp + (float) (cos(pd*3.14f)*disp);
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map_vertices[1][ii] += new_height;
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}
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}
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--num_iter;
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}
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}
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/**********************************************************************
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* OpenGL helper functions
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*********************************************************************/
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/* Create VBO, IBO and VAO objects for the heightmap geometry and bind them to
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* the specified program object
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*/
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static void make_mesh(GLuint program)
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{
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GLuint attrloc;
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glGenVertexArrays(1, &mesh);
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glGenBuffers(4, mesh_vbo);
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glBindVertexArray(mesh);
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/* Prepare the data for drawing through a buffer inidices */
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glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mesh_vbo[3]);
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glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLuint)* MAP_NUM_LINES * 2, map_line_indices, GL_STATIC_DRAW);
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/* Prepare the attributes for rendering */
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attrloc = glGetAttribLocation(program, "x");
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glBindBuffer(GL_ARRAY_BUFFER, mesh_vbo[0]);
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glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * MAP_NUM_TOTAL_VERTICES, &map_vertices[0][0], GL_STATIC_DRAW);
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glEnableVertexAttribArray(attrloc);
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glVertexAttribPointer(attrloc, 1, GL_FLOAT, GL_FALSE, 0, 0);
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attrloc = glGetAttribLocation(program, "z");
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glBindBuffer(GL_ARRAY_BUFFER, mesh_vbo[2]);
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glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * MAP_NUM_TOTAL_VERTICES, &map_vertices[2][0], GL_STATIC_DRAW);
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glEnableVertexAttribArray(attrloc);
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glVertexAttribPointer(attrloc, 1, GL_FLOAT, GL_FALSE, 0, 0);
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attrloc = glGetAttribLocation(program, "y");
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glBindBuffer(GL_ARRAY_BUFFER, mesh_vbo[1]);
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glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * MAP_NUM_TOTAL_VERTICES, &map_vertices[1][0], GL_DYNAMIC_DRAW);
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glEnableVertexAttribArray(attrloc);
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glVertexAttribPointer(attrloc, 1, GL_FLOAT, GL_FALSE, 0, 0);
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}
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/* Update VBO vertices from source data
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*/
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static void update_mesh(void)
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{
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glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(GLfloat) * MAP_NUM_TOTAL_VERTICES, &map_vertices[1][0]);
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}
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/**********************************************************************
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* GLFW callback functions
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*********************************************************************/
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static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
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{
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switch(key)
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{
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case GLFW_KEY_ESCAPE:
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/* Exit program on Escape */
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glfwSetWindowShouldClose(window, GL_TRUE);
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break;
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}
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}
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static void error_callback(int error, const char* description)
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{
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fprintf(stderr, "Error: %s\n", description);
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}
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int main(int argc, char** argv)
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{
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GLFWwindow* window;
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int iter;
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double dt;
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double last_update_time;
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int frame;
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float f;
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GLint uloc_modelview;
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GLint uloc_project;
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GLuint shader_program;
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glfwSetErrorCallback(error_callback);
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if (!glfwInit())
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exit(EXIT_FAILURE);
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glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
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glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
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glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
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window = glfwCreateWindow(800, 600, "GLFW OpenGL3 Heightmap demo", NULL, NULL);
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if (! window )
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{
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glfwTerminate();
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exit(EXIT_FAILURE);
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}
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/* Register events callback */
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glfwSetKeyCallback(window, key_callback);
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glfwMakeContextCurrent(window);
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gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);
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/* Prepare opengl resources for rendering */
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shader_program = make_shader_program(vertex_shader_text, fragment_shader_text);
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if (shader_program == 0u)
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{
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glfwTerminate();
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exit(EXIT_FAILURE);
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}
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glUseProgram(shader_program);
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uloc_project = glGetUniformLocation(shader_program, "project");
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uloc_modelview = glGetUniformLocation(shader_program, "modelview");
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/* Compute the projection matrix */
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f = 1.0f / tanf(view_angle / 2.0f);
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projection_matrix[0] = f / aspect_ratio;
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projection_matrix[5] = f;
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projection_matrix[10] = (z_far + z_near)/ (z_near - z_far);
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projection_matrix[11] = -1.0f;
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projection_matrix[14] = 2.0f * (z_far * z_near) / (z_near - z_far);
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glUniformMatrix4fv(uloc_project, 1, GL_FALSE, projection_matrix);
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/* Set the camera position */
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modelview_matrix[12] = -5.0f;
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modelview_matrix[13] = -5.0f;
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modelview_matrix[14] = -20.0f;
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glUniformMatrix4fv(uloc_modelview, 1, GL_FALSE, modelview_matrix);
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/* Create mesh data */
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init_map();
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make_mesh(shader_program);
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/* Create vao + vbo to store the mesh */
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/* Create the vbo to store all the information for the grid and the height */
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/* setup the scene ready for rendering */
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glViewport(0, 0, 800, 600);
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glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
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/* main loop */
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frame = 0;
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iter = 0;
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last_update_time = glfwGetTime();
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while (!glfwWindowShouldClose(window))
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{
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++frame;
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/* render the next frame */
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glClear(GL_COLOR_BUFFER_BIT);
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glDrawElements(GL_LINES, 2* MAP_NUM_LINES , GL_UNSIGNED_INT, 0);
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/* display and process events through callbacks */
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glfwSwapBuffers(window);
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glfwPollEvents();
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/* Check the frame rate and update the heightmap if needed */
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dt = glfwGetTime();
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if ((dt - last_update_time) > 0.2)
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{
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/* generate the next iteration of the heightmap */
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if (iter < MAX_ITER)
|
|
{
|
|
update_map(NUM_ITER_AT_A_TIME);
|
|
update_mesh();
|
|
iter += NUM_ITER_AT_A_TIME;
|
|
}
|
|
last_update_time = dt;
|
|
frame = 0;
|
|
}
|
|
}
|
|
|
|
glfwTerminate();
|
|
exit(EXIT_SUCCESS);
|
|
}
|
|
|